URGENT: Ideas for improving/fixing ADSL signal integrity???(Current noise margin is -0.2db. FAIL.)

For the past month or so, our centurylink ADSL 10Mbps internet has been hopelessly slow, and constantly dropping out entirely. Considering the router itself was having weird problems that are always fixed for 10 minutes by hard-rebooting it, Replacing the router did seem to make a difference, and made it really fast, about 9.7Mbps directly though Ethernet, and not much lower though Wi-Fi w/ 12 devices (8 wireless) attached. However that, of course, could not last, and now we find ourselves restarting the router or temporarily disconnecting the phone line to get internet to work at ALL. CenturyLink "technicians" have even come over on multiple occasions in the past to try to fix it, and nothing is achieved. They do the same sh*t I do.

Anyway, in search of digging around for a solution, I found out that the average line attenuation is 42db, and the noise margin is a jaw dropping 1 to 3db! EPIC FAIL (facepalm^2)! That's is like NO margin, considering that after googling it, supposedly a SNR of anything less than 10 means HORRIBLY unreliable internet, and I am several orders of magnitude below even that! (knowing that 3db down is half the signal) Ok I'm done ranting.

So what I am wondering is it possible to do something to improve that figure? Moving the router from the upstairs will not be easy since there is a Ethernet printer and wired computer that's in a different section of the house where Wi-Fi does not work well. Sorry for all the spelling errors since the internet is dead and if I get anywhere close to the router I am going full photonicinduction on it. Had to type this on the full 'ables site from a phone. (Also I can upload images of my screenshots when the internet begins to work tomorrow, if it ever does.)

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I was fighting the same ghosts for a long time, turned out that somewhere outside a connction was flooded.

After a line check by my ISP I insisted that someone goes out and physically inspected all.

15 minutes after the repair my connection was good and stable.

Also using the right modem helps a lot, I "upgraded" to a dirt cheap TP-Link modem as I never liked the one my ISP supplied, this modem improved up- and download speeds by around 20% and on top of that my WiFi range more than doubled allowing me to use the internet even in the closed up garage (tin roof and walls).

-max- (author)  Downunder35m2 years ago

Are you saying that somewhere the line has been actually flooded? like with water causing a short or something?

That is what I am saying, especially old lines with a lot of connection / junction points can fail.

Call your provider and request a full line check also use a different modem for a test.

If the line is not 100% request an inspection of the line - they will tell you have to pay if there is no fault but unless you have a faulty modem or problems with the wires in your house it is the best bet.

-max- (author)  Downunder35m2 years ago

I will keep that in mind tomorrow and see what else I can discover. Is it possible to probe the phone lines with an 30MHz analog oscilloscope to determine if it is something like rise/fall times or something that would indicate just too long a wire?

SHA129 months ago

I had a somehow similar problem, my connection was unstable and I had a low SNR Margin of about 6 db. Finally turns out that the cause of the problem is a high distance of about 5km from home to the ISP.

Finally I changed the Modulation of my modem from ADSL2+ to G.DMT, and the problem was totally solved!

I'm not an IT expert, but based on information on Wikipedia, G.DMT enjoys special noise cancellation algorithms and is suitable for some kilometers long copper lines. however it's bandwith is limited to 8Mbps.

-max- (author) 2 years ago

I have replaced the internal wiring inside the house with a shorter, more direct length of phone wire going directly to the juntion box outside. It has been that way for a over a month now, and it NEVER dropped out, and has been right up at 9.5mbps or better all the time, I think the slowest it has ever got was like 7.5, which is absolutely understandable and forgivable.

seandogue2 years ago

I'm not *clear from your post.

Have you had your *external lines checked? I live in an inner ring suburb, and our lines are quite old. Occasionally one will go down and they have to reroute to another channel, or the repeater mounted in one of those ground or pole mounted boxes will experience the effects of a lightning strike and need replacement. Still functional (sometimes), but at diminished capacity...

In the past decade, I've had the lines checked and serviced ~ a dozen times. Each time, it has been at the cost of the provider, as is required by law. I pay for a 24M-down, 3M-up channel, and I expect a 24M-down, 3M-up channel or better.

Point of note: AFAIK, service providers, be they the traditional tele companies or the cable providers, have a federally mandated responsibility to maintain a minimum S/N level. and throughput (with obvious emergency exceptions like a downed pole or similar).

Ask yourself this...When the service techs have come out, have they presented you with a report of the service line S/N or the internal system S/N? If those numbers are service line then they have a problem on the poles, the repeaters, or the distribution hub that they need to and are legally required to address. If it's internal only, then you need to check your wiring and equipment and fix whatever is gone vercrapped

-max- (author) 2 years ago

Here is a snapshot of the probable issue:

Untitled.png
Vyger2 years ago

I am tending to agree that there is a line problem. Something chewed or frayed and lets just enough moisture in to make a lot of noise. Or it could be a defective transformer close by causing problems.

I once had a lady running dialup (yes still) and it kept disconnecting. I noticed she was doing laundry and every time the washer motor would turn on the modem would drop. Turns out the phone line was running behind the washer and the motor put out a spike that made the modem drop the connection. The solution was for her not to do laundry when she wanted on line.

Weird things happen sometimes.

-max- (author)  Vyger2 years ago

Intresting. I was sort of suspecting that, considering that the phone line goes a long way before it reaches the modem/router. I did move it to the downstairs and it seemed to get faster, but then again it always does since it was reset, and it did eventually drop out the same way again. I could not keep it down their since the business computer it critical and is wired w/ ethernet for reliability.

-max- (author) 2 years ago

The internet just now completely dropped out and when it reestablished a connection, the noise margin went back to to around 9-10db. While that high, it works OK, and internet speeds are around 5mbps. Fast enough for my needs. However it never stays that high. It will degrades linearly over time, until eventually internet is lost completely, then I have to reestablish the connection manually. :(